Keep Cool

An energy auditor can help ensure your new AC unit is sized correctly for your home. A unit too large or too small can create inefficiencies.

Many homes may have an older air conditioner (AC) — say 15 years old — that’s not the most efficient but still works. When should those units be replaced? Upgrading to a more efficient model could significantly reduce your electric bill, and replacing an aging system now, before summer starts, could help you avoid delays or price premiums.

The best way to determine possible savings is to have an in-home assessment conducted by a qualified heating, ventilating and air conditioning (HVAC) professional or a certified energy auditor. Electric co-ops are often interested in reducing peak summer loads and sometimes offer rebates or a list of qualified professionals. It’s a plus if the contractor has North American Technician Excellence (NATE) certification. Contractors should be knowledgeable about energy efficient systems and have good references.

Your contractor needs to size the system to your home. A unit that is too small will not cool your home to the levels you want. If it is too large, it may not dehumidify your home sufficiently and will cycle on and off more frequently, which can increase wear and tear on the system and shorten its life significantly.

In order to size the system, the contractor will need to look at the efficiency of the home by checking insulation levels. If you add insulation where it’s most needed, you may be able to install a smaller AC unit, and you should enjoy greater comfort and lower cooling costs. The HVAC contractor you hire should also assess your ductwork, which is often poorly designed, leaky or inadequately insulated.

As you talk to your contractor, it’s good to know there are several air conditioning options suited to different situations. It may or may not be practical to change to a different type of system.

Central air conditioning is generally one of two types: either split or packaged. A split system, which has the cold coils inside the home and an outside unit exhausting heat, is the most common. Packaged systems, which are sometimes installed because of space constraints, combine these functions into one box located outside the home.

A heat pump can provide cooling and heating in homes with or without ducts. If you are currently using propane or natural gas as your fuel source, this may be a good option.

A ductless mini-split heat pump can be an efficient way to cool up to four zones inside the home. If your existing ductwork is in bad shape or poorly designed, this could be a good solution.

Window units are much less efficient than other options, but they can still be effective for cooling a single room. It’s worth paying a little more for a new Energy Star-compliant unit, rather than the dusty $80 unit from the yard sale or auction that wheezes its way through the summer.

Evaporative (or “swamp”) coolers are an alternative in very dry climates. While they use a quarter the energy and are less expensive to install than central air conditioning, they also require more frequent maintenance.

Replacing an aging air conditioner is a great way to improve comfort, cut energy costs and reduce peak energy demand. Your co-op may be able to help, and you can learn a lot from the information resources available on our website and on the Energy Star and energy.gov websites.

About the Author

This column was co-written by Pat Keegan and Amy Wheeless of Collaborative Efficiency. For more ideas on energy efficient landscaping, visit: collaborativeefficiency.com/energytips.